Adjustable eccentrics for sewing machines



April 30, 1957 B. P. PINKVOSS ADJUSTABLE ECCENTRICS FOR SEWING MACHINES Filed Sept. 12. 1951 IN VEN TOR. ofierihold @z'nhvoss WITNESS ATTORNEY.

United States ADJUSTABLE ECCENTRICS FOR SEWING MACHINES Application-September 12, 1951, Serial No. 246,257

7 Claims. (Cl. 74-571) The present invention relates to improvements in adjustable eccentrics for use in sewing machines and has for its primary object to provide an adjustable eccentric of simplified design which is compact and in which the component parts are resiliently maintained in selected position of adjustment.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, a presently preferred embodiment of the invention is hereinafter set forth in such detail as to enable those skilled in the art to readily understand the function, operation, construction and advantages of it, when read in conjunction with the accompanying drawings, in which:

Fig. l is a fragmentary horizontal sectional View through the bed of a sewing machine which includes an adjustable eccentric constructed in accordance with my invention.

Fig. 2 is a vertical section taken substantially on the line 22 of Fig. 1.

Fig. 3 is a vertical section taken substantially on the line 33 of Fig. 1.

Fig. 4 is a detail view showing the eccentric element per se.

The present improvement has been embodied in a sewing machine of the type set forth in my co-pending U. S. patent application Serial No. 217,937, filed Mar. 28, 1951, now Patent No. 2,678,010 issued May 11, 1954, to which reference is made for a more complete understanding of the details of the machine. It is to be understood, however, that this machine has been selected only for purposes of illustration.

Referring to the drawings, there is shown a sewing machine bed 1 having walls 2 and 3. Journaled at one end in a bearing bushing 4 in the wall 3 is a driven rotary shaft 5 having fixed thereto by screw 6 a driving collar or flange 7. A guideway 8 having undercut edges is formed in one face of the flange 7, which guideway slidably receives a beveled-edge slide-plate 9. Disposed between the slide-plate 9 and guideway 8 along one of the mating side-edges thereof is a gib 10 secured in the desired position by a screw 11 threaded through a bore 12 in the flange 7.

Formed integral with the slide-plate 9 is a feed-driving eccentric 13 having an aperture 14 through which the shaft 5 extends and which aperture communicates with a corresponding shaft-clearance aperture 15 in the slideplate 9. A two part eccentric-strap 16, secured together by screws 17, embraces the eccentric 13. Integral with one-half of the strap 16 is a pitman 18 connected by a ball and socket joint to the one end of a link 19, the other end of which is connected to a one-Way clutch 20 operatively connected to a vertical feed-wheel actuating shaft 21. Thus it will be seen that,.as the shaft 5 is rotated, intermittent one-way rotation will be imparted to the feed-shaft 21 by the above described structure.

The eccentricity of the eccentric 13 is made adjustable with respect to the shaft 5 in the following manner. The aperture 14 in the eccentric 13 is formed substantially aent Hce

larger than the diameter of the shaft 5 and is elongated in a direction transverse to the longitudinal axis of the slide-plate 9. On the two opposite faces of the aperture 14 that are in line with the longitudinal axis of the slideplate 9, there are provided bosses 22, the opposed faces of which are parallel and spaced apart a distance equal to the diameter of an adjusting eccentric 23 loosely surrounding the shaft 5 and disposed between and in surface contact with the opposed faces of the bosses. These bearing faces on the bosses 22 are large enough so that in all positions of adjustment of the eccentric 23 a diameter thereof will be disposed between them. The transverse elongations of the aperture 14 are made large enough so that the eccentric 23 will not contact the walls thereof at any place other than at the bearing faces of the bosses 22. To permit the slide-plate 9 to move relative to the shaft 5, the aperture 15 is made larger than the shaft 5 to such an extent'that a clearance is provided between the walls of the aperture and the periphery of the shaft that is greater thanthe maximum throw of the eccentric 23 in both directions from its median position.

To limit the relative rotation between the eccentrics 13 and 23, there is provided a pin 24- secured to and projecting from the face of the eccentric 13 which is adapted to contact stop-faces 25 and 26 of a stop-plate or flange 27 integral with the eccentric 23. When the pin 24 has been moved into engagement with the stop-face 25, the eccentric 13 has been set for its minimum throw, and when the pin 24 has been moved into engagement with the stop-face 26, as illustrated in the drawings, the eccentric 13 has been set for its maximum throw.

Integral with the adjusting eccentric 23 and the stopplate 27 is a flange 23. The integral assembly which comprises the eccentric 23, stop-plate 27 and flange 28 is loosely mounted upon the shaftS and biased toward the driving flange 7 by means of a heavy coil spring 29 surrounding the shaft 5 and abutting at one end against the free face of the flange 2? and'at the other end against an adjustable collar 30 fixed to the shaft by screws 31. Motion of the integral assembly including the stop-plate 27 toward the flange under the resilient action of the spring 29 is limited by engagement of the stop-plate 27 against that face of the eccentric 13 opposite to the slideplate 9, which engagement gives rise to frictional resistance that is suficient during normal operation to prevent any relative angular movements between the eccentric 13 and stop-plate 27, thus maintaining the parts in their adjusted relationship.

In order to eifect an adjustment of the feed-driving eccentric 13, it is necessary to force relative rotation between the eccentric 13 and the adjusting eccentric 23. To accomplish this, there has been provided a detent 32 adapted to be seated in a recess 33 in the flange 28 and carried by a latch-arm 34 keyed to one end of a shaft 35 journaled in a bearing bushing 36 secured in the wall 3 and an integral boss 37 extending from the wall 2. At its other end, the shaft 35'l1as an actuating arm 38 secured thereto as by a screw 39. A spring 40 biases the detent 32 away from the recess 33, which motion is limited by a screw 41 threaded into the wall 3 in the path of travel of the arm 38.

To vary the feeding cycle of the machine, the actuating arm 38 is moved in the direction of the arrow in Fig; 2, which moves the detent 32 into engagement with the periphery of the flange 23. Withthe arm 38 held'in this position, the shaft 5 is rotated by handuntil the detent 32 engages the recess 33. In this position the flange 23 and consequently the adjusting eccentric 23 and stop-plate 27, are held against further rotation with the shaft 5. Thereupon, continued rotation of the shaft 5 will effect relative angular movement between the eccentrics :13 and 23, against the frictional resistance between the face of the eccentric 13 and the stop-plate 27, which imparts movement to the eccentric 1 3 with respect to the shaft 5 in the direction of the longitudinal axis of the slide-plate *9, thus varying the eccentricity of the eccentric 13, with the slide-plate 9 providing a shiftable driving connection between the flange 7 and the eccentric 13. Upon reaching the desired setting, the arm 38 is released, whereupon the spring 29 frictionally maintains the eccentrics 13 and 23 together in their adjusted relation.

The function of the spring 29, as will be evident from an understanding of the foregoing disclosure, is to urge the elements into a compact assembled relationship, i. e., the spring urges the stop-plate 27 into engagement with the -feed-driving eccentric 13, which, in turn, urgesthe slide-plate 9 against the driving fiange 7. The frictional engagement between the stop-plate 27 and eccentric 13 eliminates the necessity of providing a positive interlock between the feed-driving eccentric 13 and the adjusting eccentric 23, which, of course, constitutes a simplified and less expensive construction. Also, since the various parts are all biased together, the possibility of accidental displacements or any relative movements between them are reduced, especially chatter which tends to destroy the contacting surfaces and to produce undesirable noise.

In particular, it will be evident that as the feed-driving eccentric 13 rotates, forces are transmitted through the pitman 18, which forces are not uniform since the feeding is intermittent. The reaction from these forces must be taken up in the shaft 5. Because of the surface-to-surface contact between the eccentrics 13 and 23 at the bosses 22, these forces can be directly transmitted to the shaft when these surfaces are properly positioned relative to the pitman 18. However, during the greater portion of the cycle of rotation, these forces are transmitted to the shaft 5 through the eccentric 13, slide-plate 9 and collar 7. Since the eccentric 13 is supported in cantilever-like fashion, there are produced bending forces tending to tear the slide-plate 9 out of the groove 8 in the collar 7. Although this bending force is relatively small, it is intermittent which causes a tendency to chatter which is especially undesirable and destructive because of the high speeds involved. In accordance with this invention, the chattering is resisted and effectively eliminated by the action of the spring 29 that forces the slide-plate 9 into the groove 8 in the collar 7.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a sewing machine, a rotary shaft, a collar fixed to the shaft, ardriving eccentric disposed upon said shaft in adjustable driven relationship with said collar, an adjusting eccentric loosely disposed on said shaft and operatively associated with said driving eccentric to vary the eccentricity thereof with respect to said shaft, a latch to lock the adjusting eccentric against rotation with said shaft, and a spring biasing the adjusting eccentric against the driving eccentric and in turn biasing the driving eccentric against the collar.

2. In a sewing machine, a rotary shaft, a collar secured to said shaft, a driving eccentric adjustably disposed upon said shaft, a transversely slidable tongue-and-groove driving connection between said eccentric and collar, an adjusting eccentric loosely mounted upon said shaft and adapted to engage the driving eccentric for relative rotation of said eccentrics to vary the eccentricity of the driving eccentric, and a spring urging the adjusting eccentric against the driving eccentric and in turn urging the driving eccentric against said collar.

3. In a sewing machine, a rotary shaft, a collar secured to said shaft, a driving eccentric disposed upon said shaft, a slidable driving connection between the collar and driving eccentric confining said eccentric to adjustment in a single line radially of said shaft, an adjusting eccentric loosely mounted upon the shaft and operatively associated with said driving eccentric to vary the eccentricity thereof,

said adjusting eccentric having a face adapted to abut against that face of the driving eccentric opposite to the one adjacent the collar, a latch to secure the adjusting eccentric against rotation with the shaft, and a spring for urging the driving eccentric and the adjusting eccentric toward the collar.

4. In a sewing machine, a rotary shaft, a collar secured to said shaft, a'driving eccentric disposed upon said shaft, a slidable driving connection between the collar and driving eccentric confining said eccentric to adjustment in a single line radially of said shaft, an adjusting eccentric loosely mounted upon the shaft and operatively associated with said driving eccentric to vary the eccentricity thereof, said adjusting eccentric having a face adapted to abut against that face of the driving eccentric opposite to the one adjacent the collar, a latch to secure the adjusting eccentric against rotation with the shaft, a second collar fixed to said shaft and spaced from the adjusting eccentric, a spring interposed between the second collar and adjusting eccentric to urge the two eccentrics into engagement with each other and toward said first mentioned collar, which engagement frictionally locks the two eccentrics together during normal operation.

.5. In a sewing machine, a rotary shaft, a collar secured to the shaft, a feed-driving eccentric formed with an enlarged shaft-receiving aperture disposed upon said shaft and adjustably associated with said collar to be driven thereby, an adjusting eccentric loosely mounted upon said shaft and disposed within the shaft-receiving aperture of the feed-driving eccentric, a latch to lock the adjusting eccentric against rotation with the shaft, and a spring acting am'ally of said shaft for urging said adjusting eccentric into engagement with the feed-driving eccentric and for urging the feed-driving eccentric against the collar.

6. In a sewing machine, a rotary shaft, a collar secured to the shaft, a feed-driving eccentric formed with an enlarged shaft-receiving aperture disposed upon said shaft and adjustably associated with said collar to be driven thereby, an adjusting eccentric loosely mounted upon said shaft and disposed within the shaft-receiving aperture of the feed-driving eccentric, said adjusting eccentric and shaft-receiving aperture in the feed-driving eccentric being of such form and size that only single-line motion will be transmitted to the feed-driving eccentric upon rotation thereof relative to said adjusting eccentric to vary the eccentricity of the feed-driving eccentric, a latch to lock the adjusting eccentric against rotation with the shaft, and a spring acting axially of said shaft for urging said adjusting eccentric and the driving eccentric into engagement with each other and toward said collar into a compact assembly.

7. In a sewing machine, a rotary shaft, a collar secured to said shaft, a driving eccentric formed with an enlarged shaft-receiving aperture disposed upon said shaft and radially adjustable relative thereto, a slidable driving connection between the collar and a first face of the driving eccentric limited to sliding movement in a single line, an adjusting eccentric loosely mounted upon said shaft and disposed within the enlarged shaft-receiving ap erture in the driving eccentric, said adjusting eccentric having a flange-like stop-plate projecting radially therefrom and adapted to abut against a second face of the driving eccentric, a latch to releasably secure the adjusting eccentric against rotation with the shaft, and a spring acting axially of the shaft for urging the stop-plate of the adjusting eccentric into engagement with the second face of the driving eccentric and in turn, for urging the first face of the driving eccentric against the collar.

References Cited in the file of this patent UNITED STATES PATENTS (Other references on following page) 5 UNITED STATES PATENTS 2,128,031 Dubi Dec. 15, 1925 2,678,010 Gruman May 9, 1933 Terrell July 2, 1935 Stearns Ian. 28, 1936 5 17,779 Horton June 7, 1938 of 1396 6 Myers Aug. 23, 1933 Pinkross May 11, 1954 FOREIGN PATENTS Great Britain Aug. 11, 1896 

